Electric baking-oven.



, J. I. AYER & H. B. GALE.

ELECTRIC BAKING OVEN. 5 APPLIOATIOH FILED NOV. 11, 1909.

I ,I Tower-152:0 71g: 1

Horace UNITED sTA s P ENT oEFIoE.

JAMES I. AYEB, F CAMBRIDGE, AND HORACE B. GALE, 0E NATICK, MASSACHUSETTS,

ASSIGNOBS To SIMPLE): ELECTRIC HEATING COMPANY, orv CAMBRIDGE, MASSA- CHUSETTS, A coEroR TIoN or MASSACHUSETTS.

ELECTRIC BAKING-OVEN Specification of Letters Patent.

T0 at! whom it may concern:

Be it known that we, JAMES I. AYER, a

citizen of'thc United States, and a resident of Cambrid e, in the county of Middlesex and State 0 Massachusetts, and Homes B. GALE, a citizen of the United States, and a resident of Natick, in'the county of Middlesex and State of Massachusetts, have finvented an Improvement in Electric Baking Ovens, of which the following descri tion,

in connection with the accompanying rawings, isra specification, like letters on the drawings representing like parts.

' The objects of our invention are to produceia compact electric oven having a plu-' rality *ofshelvesfind having provision for an even distribution of heat on the top and bottom-of each shelf, while delivering the :heatirom a" single place in the oven, also to prltivide independent heat regulation for 'o'n'e or agr'oup off "shelves independently' 'o-lf the others,-andmeans for entirely shutting 0113* theflheat from a portion of the 'o'vnf when'deeired, so as to diminish the' zii efl'ecltive working space and thereby economining the electric energy, when the oven is less than its in] capacity of work.

The constructional details and various ad vantages ogtou-r' invention will appear more -f i1lly1n the course of the following detailed taken" with reference to the facqfimpanyin drawings in which we'have shown pre jerre'd embodiments of the invencan.

the d'rawings,,Figure 1 is a vertical transverse Sectional view of the oven Fig. front view thereof, partly in section; ig. 3 a horizontal sectional ,view on the line-34., Fig. 1; Figs-'4.- and'5 are-frag- -'0 inen'tary sectional details of a modified -coi1-. struction viewed respectively from the front and from the side; and Figs. 6 and 7 are enlarged details of the electric heater.

The shell 1 of the oven consists of double walls-2 packedwith heat insulating materi aIBclosedon all sides excepting the front, where the o ening 4 isclosed by any suit able doors, 5 erein shown as two swin i'ng doors 5 constructed the same as 'the we ls 2 and. hinged at 6 to saidwa-lls. The electric heater is located at the bottom of the oven and'is herein indicated at. 7 '8,-l..9, a flue 1O leading therefrom at the ba'clr o f the heater,

the back wall of the oven constituting theback wall of the flue, and a metal wall or partition 11 the front wall of the flue. From 1'the bottom of this metal wall leading forwardly and downwardly is a closed partition 12 separating the lower part or heating chamber 13 from the upper part or baking chamber. In the baking chamber are arranged shelves 1 1 of any usual or preferred kin At the front end of the partition 12 an apron 15 extends downwardly approximately parallel to the front wall 16 ot the oven to within a short distance of the bottom to form a return air line 1.7. Thus it will be seen that as there is a free upward passage or flue 10 for the escape of the hot chamber 13 and as the flue 17 opens at 18 at the bottom of the-chamber 13, a continuous circulation of the heated air is compelled in the direction of the arrows. This is further facilitated by the fact thatjhe back fectly ti ht, retain the heat better than the than 'said front walls or doors so that the hotrear wall of the. 'oven facilitates the upward movement of the air while the cooler doors promote t-e downward movement of the air, which y that time has become slightly cooler than w'nen'it left the heating chamber. 13 n its upward passage in the 'fl'ue 10.

In the back metal wall or partition '11 we provide-a series of openings'or hot air ports 19,20, 21,- 22, 23, preferably. graduated in size, the lower ports being lar er and decreasing successively to the sum lest ort at 1 9, These ports extend horizontally ust bengath the shelves or in other words, f t-the top of each baking 'c'mpartment, .fiereby tr smitting the heat re'otly to the bottom '0 -a',shelf,' for maintaining Said shelf-properly heated, and directly over or on time of the articles beingbaked, so that said'agi ticles receive an even distribution of he :"ab and below; The. partition 12 and; protect the lower part of the baking from direct radiation from the eleptric heaters in thfiheatingchamber, Meanis are .pro-

the preferre means comprising swinging dampers Q5," pivoted at their u er sides at 26 and operated "b' a rod 2'1 external handle 28 pre'ferab y ith notches p il-it Patented Nov. 8. 1910.

air from the highest point of the heating walls of the oven, being thicker and perfront we ls or doors and hence'become hotter l chamber -vided for regulating each air port 19-2-3,

2?) to engage the bottom of the slot 30 llirougll \Yllltll they operate in the iron! \rall oi the oven. in Figs. l and i), we have shown the back wall as composed of a series;

5 of plates 3] adjustable by means of slot... i:

ll'icrein engaged by set bolts 33 operating in side uprights 34. The line is preferably slightly flaring, being; smaller al. the top than at the bottom. The reason for pro 10 viding for a lar er entrance for hot air at the bottom of t e flue 10, Where, as previously stated, the openings are preferably larger into the lower ovens than into the upper ovens, is to promote uniformity of heating effects, as We have found that it each compartment of the baking chamber is provided With the same sized opening or if the dampers are left open exactly the same in all the con'rpa'rtments, the uppermost compartment will be greatly overheated and the lower compartments will be underheated.

It will be apparent that the arrangement of fines is such as to make the air circulation powerful and certain in direction. As the fine 1'? is carried down to the bottom. of the heatixiig chamber considerably below the partition l2, and the fine 10 leads from the top of said heating chamber, it follows that. the time 10 is the only path by which so the air can. naturally escape from the heating chamber. The natural. path for the hot air from the electric heaters is therefore up the flue 10 and through the openings Ill--23, and, as just explained, in order to force the hot air to distribute itself properly among the different chambers and over and under the different shelves of the oven,'the openings or airports are restricted in area, being smaller at the top of the'oven where -10 the airpressure becomes the greatest, and

gradually becoming larger therefrom toward the bottom, where the pressure of the air column is less, their area being inversely proportional to the air velocity at the given points in thefiue 10, so that a-very uniform distribution of heat is obtained on the differ-cut shelves of the oven. This heat regu lation may be permanently setfor distriburine the heatas in Figs. 4 and 5, or hand controlled by the dampers 25. which may be held in adjusted positions as shown in Fig. 1. An advantage of the adjustmentshown in ,Figs l: and. 5 is that it makes it possible to specially adjust for prolonged use any given shelf for any special work required of that compartmentof the heating chamber, so that one compartment may be permanently set to be abnormally hot or abnormally cold as compared with the rest. The hand operat-ed dampers provide means for accomplish ing the same. purpose temporarily, so'that the hot air supply may be-varied in any manner desired momentarily or otherwise,

as may be required. The dampers make itpracticable to out ofithe hot air supply ---z1 -za;g arrangement at altogether from any shell. Tn thisease the shelves will of course be solid instead of in the form of grid irons, although for gen eral purposes we do not limit this fei'iturc of our invention to any inirticulanconstruc-- tion. 'lo permit the entire closin r of a given portion of the oven, we prefcraF-ly provide at a desired point or points a slide partition 35, preferably corhmaserl in Whole or in part of heat insulating i'naterial, said slide partiljion being mounted on an angle iron or guide 36 so that it can be shoved in place as shown in I ig. 1. so as to cut of]? the upper portion. of the oven and fines, or removed, thereby restoring the entire oven to normal use. This arrangement does not interfere in. any way with the proper circulation the hot air in the section below this. damper partition or cut-oil. This permits the amount of electric current going to the electric heat ers to be correspondingly reduced so that the oven may thus be run more economically for a small baking.

ln l i s. t3 andv 7 are illustrated more in detail the preferred type and arrangement as of electric heaters which are especially adaptei'l and arranged to cooperate with an oven or" this cliaracter, in which, in order to get a nniforn'i distribution of heat in all. parts of the oven, it is necessary to have a- 9-5 rapid and powerful circulation of air.. If the air'currcnts were slow the air would be cooled in passing across, for example, from the back to the front side of the oven be tween the sllel\.-'es so that the, baking would be uneven, the back side of the shelf being hotter than the front side. By providing lion-own: a large unobstructed flue space for the passage of the air, excepting as necessarily limited by the controlling ports 1923, and giving positive direction to the air current by the arrangement of the flues. already described, the circulation of the air is so rapid that the temperature is practi cally the same at the front and back of each shelf To accomplish this unobstructed passage of the air at the heating point, the heaters are made in the form of'flat plates or grids 37 arranged in parallel planes With} a comparatively wide intervening air space, said plates being set edgewise vertically 0 parallel to the flow of the air so as tQ- struct it as little as possible. In Fig this flat plate, of zig-zag arrangement with air insulation 38, ail'ords a high resistance path for the current between. the/terminals 39, 40. These plates are mounted in ,aserieiflv on rods 4:]. surrounded by an insnlation' covering l2 tightly fitting the holes 43 the, stampings or plates 37. The ends terminate in bosses 44. separated in pairs lay insulation rings 45 so that thebosscs of .pair "0 plates contact with eachaother' air-arm w ll be. readily pndergtog,

7, so that the current is caused to traverse the lates in series. At the ends of the rods 41 t e plates are clamped by nuts 46, washers .47 andinterposed insulation 48. These rods are attached to the side walls of the oven so as to hold the plates in position. The, a small rods, being the only parts of the electric heater construction that run transversely tothe air current. oti'er very little obstruction to the free flow of-air. This construction and arrangement of heaters contributes materially. to the successful operation ofthe oven. it combines with the special flue arrangement or system of air cir-- culation to produce a circulation. sutliciently positive and rapid'to permit coiicentrating the electric heaters at one point, where they are well protected, while still attaining practically a uniform heat in all parts of thg baking chamber;

i; will be understood that the proportions ,of the oven and various details of the arrangement. will be varied to suit. the pan.

ticular space or other arrangement where the oven is to be ins alled, and that, in general, many variations in details may he resorted to without departing from the spirit and scope of.onr invention as defined in the'following claims.

Having described our invention, what we claim-as new and desire to secure by Letters Patent is,

1-. Incombinat ion,an electrically heated oven inclosurc, a baking chamber therein, having. a series of Shelves spacer. oneabove the other,-a heating chamber belon and sepa rated from the baking chamber in said inclosure, electric "heating elements in said heating chamber, a .cool air fine from one portion of the baking chamber opening into the-lower part of the heating chamber, and

a hot air flue extending upward from the upper portion ofthe heating cha'i'nber to the baking chamber.

2. In combination, an electrically heated oven .inclosure, 'a'baking chamber therein, havin the of er, a heating chamber below and separated from theibaking chamber in said inclosure, '-electr1c heating elements in said heating chamber, a cool a1r flue from one portion of the baking chamber opening into the lowbr part of the heating chamber, a. hot air flue extending. upward from the the baking chamber, and means to regulate the delivery of hot air to the. different shelves.

.3. In combination, an electrically heated oven 111c1osure,;a"'bakmg chamber therein,

.-c1osu're, electric heating. elementsein" said heating chamber, a cool air flue" from one a series of shelves spaced one above,

-upper-,portioii (if-the heating chamber to I portion of the baki chamberopening into the lower part of tie heating chamber, ahot air flue extending upward from the per portion of the heating chamber to t e baking chamber, and ii'idcpeinlent heat.- regulating means for controllin the delivery of hot air from said hot air note the (littercnt shelves.

4. In combination, an electrically heated oven inrlosure, a baking chamber therein, having a series of shelves spaced one above the other, a. heating chamber below and separated from the baking chamber in said inclosure, eltmtricl'ieating elements in said heating chamber, a cool air flue from one portion of the baking chamber opening into the lower part of the heating chamber, a hot air flue extending upward from -t hc=upper portion of the heating chamber to the aking chamber, and means-to regulate the temperature of the ditterentshelves, consist ing of air ports opening from said hot; air line into the baking chamber oversaid respective shelves graduated in size so as to present less area for the admission of air at the upper levels than at the lower levels.

5. In conibinatioi'i, an electrically heated oven inclosure,- a baking chamber therein, having a series of shelves spaced one above the other, a heating, chamber below and separated from the bakin chamber in said inclosure, electric heating elements in said heating chamber, a. cool air fine from one portion of the baking chamber opening into the lower part of the heating chamber, a

hot airflue extending upward from the upper-portion ofthe heatingchaniber to the baking chamber, and means toshut off the the other, a heating chamber below and sepa-' rated from the baking chamber in said inclosure, electric heating elements consisting of conducting lates set vertically edgewise I,

to the normal ow of the air current in said heatingchamber, a cool air line from one portion of the baking-chamber opening into the lowe'r part. of the heatingchamber, and a hot air flue extending 'upwai'd'from the upper portion of the heating chamber to the baking chamber.

7 An electrically heated oven, comprising an inclosing shell having-a baking chamher, a series of shelves thereinspaced one above the other, a heat-in" chamber in said shell below and separated from the baking chamber, electric heating elements consisting of conducting plates set vertically edge wise to the normal flow of the air current in said heating chamber, a cool air-flue from pine portion of the baking chamber opening into thelower-ipart of thefhoatingchamber,

iii.

. below an se state from the baking chamber, electric eating elements, comprising a series of resistance, conductors in the form of parallel flat grids-set vertically edgewise, mounted and clampedtogether on horizontal rods in said heating chamber so as to offer a inimum resistance to the flow of air in its normal course, a cool air flue from one portion of the baking chamber opening into the lower part of the heating chamber, and a hot air flue extending upward from the upper portion of the heating chamber to the bakin chamber. Y

9. n electricall heated oven, comprising an inclosing shell 'aving a baking chamber, a series of shelves therein spaced one above the other a heatin' chamber in said shell below and separate from the baking chamber,- electric heating elements, comprising a series of resistance conductors in the form of parallel flat grids set vertically edgewise, mounted and clamped together on horizontal rods in said heating chamber so as to other a minimum resistance to the flow of air in its normal course, a cool air flue from one portion of the baking chamber opening into the lower part of the heating chamber, a hot air flue extending upward from the upper portion of the'hea'ting chamber to the baking chamber, and means to regulate the delivery of hot air to thediffcrent shelves.

10. An electrically heatedloven, comprising an-inclosing shell having a baking chain.- bar, a series of shelves therein spaced one above the other, a heatin chamber in said shell below-said baking chamber, a hot air. flue opening from the .top of said heating chamber adjacent the back, closed wall of the oven,,-a, coql air flue located at the opposite .cooler'entrance side of the oven .and opening into said heating chamber at the bottom thereof, said heating chamber having its upper 'wallseparated from the bottom shelf of the baking chamber by an air s ace and inc-lined upwurdly and rearwardly rom vthe inlet openmg of the cool air flue-to-the.

entrance opening of the hot ainfiue, electric heating elements mounted together in said heli'ting' chamber, and separate hot air ports from said hot air flue into the individual bak-- ing com'partments between adjacent shelves.

abovethe other a heatin 11. An electricall heated oven, comprising an inclosin she I having a baking chamher,- a series 0 shelves therein spaced one chamber in said shell below said baking 0 amber, a hot air from the top of said heatin chamber a jacent the back, closed wall 0? the oven, a cool air flue located at the opposite cooler entrance side of the oven and opening into said heating chamber at the bottom thereof, electric heating elements mounted together in said heating chamber, and a separate hot air .ort from said hot air flue into the baking 0 amber at the top of eiilchfbaking compartment formed above each s e I 12. An electrically heated oven, comprising a heat insulating shell, electric heating elements therein, a baking chamber in said shell, and means for controlling the distribution ofheat from said'heating elements to said baking chamber.

13. An electrically heated oven, comprising a heat insulatin g'shell, electric heating V elements in the base thereof, a baking chain her in said shell arranged relativel to said heating elements to permit a circu ation of air therethrough and therefrom, and means for controlling the distribution of heated' air to said baking chamber.

14. Anelectrically heated oven, compris-v ing a heat insulating shell, an electric heat? ing element in the base thereof, a baking chamber above said heating element, a passageconstructed to circulate heated air from said heating element to the baking chamber at one side of the oven, a passage bein arranged to conduct cool air from the ba ing chamber to the heating element along an other side of the oven, and a door on saidsecond side adjacent said cool air passage.

15. An. electrically heated oven, comprisinga heat insulating shell, electrlc heating elements therein, a baking chamber arrangedv for the circulation of air to and from said electric heatingelements, means for controlling the distribution of heated air to said baking chamber, consistin of a series of dampers havlng operating evioes extending to a side of stud shell, and a door on said side.

In-testi'mony whereof, we have signed our names'to this specifioati0n,-in the presence of two subscribing witnesses. a

- JAS. I. AYER. HORACE B. GALE.

\Vitnesses: v

Done A. Pno'o'ron, ELIZABETH M. COiU'JiN. 

